There is, however, one major drawback: being on the open seas means that for up to 20 hours at a time he is completely cut off from the outside world, including his girlfriend Meghan Markle.

With no mobile phone signal, no internet and only the ship’s radio for essential communications, the Prince has not been able to phone or message American Miss Markle with the sort of frequency he might have liked.

Prince Harry and Meghan Markle will not be able to contact each other for up to 20 hours at a time during his tripCredit:
PA/Getty

It meant Miss Markle had to celebrate Thanksgiving - the day when North Americans will do anything to be with their loved ones - largely without contact from the man in her life.

While she was posting an Instagram picture of herself with an enormous roast turkey, the Prince was carrying out his public duties on behalf of the Queen.

He embarked from St Kitts and Nevis on Wednesday night for a 20-hour overnight voyage to St Lucia, which gave him plenty of time to get to know most of the 72 crew members who are ferrying him between islands.

He has already found his sea legs and has had no difficulties with seasickness, despite being a soldier rather than a sailor by trade.

But while the Prince loved being just one of the lads when he was a serving soldier, his status as a VIP guest aboard the RFA Wave Knight means he has been given the captain’s cabin, in line with standard protocol.

All members of the Royal family or senior naval figures are given the captain’s cabin as a gesture of respect and hospitality, though the spartan room is barely any different from the other billets in the officers’ corridor.

The Prince does not get any special treatment and nor would he ever want any from the crewsource on Prince Harry's time on board RFA Wave Knight

The Prince will be spending a total of six nights on board Wave Knight, which has been moored a mile or so out to sea during his visits so far to Antigua and Barbuda and St Kitts and Nevis.

It is performing the task once fulfilled by the Royal Yacht Britannia, though unlike the former Royal Yacht he is not able to invite local dignitaries on board because the ship is a working naval vessel.

A source said: “He is really liking life on board, he took to it immediately and he is enjoying getting to know the crew and talking to everyone he meets."

“He is eating his meals with the team and the officers on the ship, in the mess with the other sailors. It is very traditional fare, a standard English breakfast and good, no frills food for other meals when he is on board.

“The Prince does not get any special treatment and nor would he ever want any from the crew.

“He has, though, been given the captain’s cabin, in line with standard protocol when the ship hosts a member of the Royal family or a senior naval figure, and he is incredibly grateful for that.”

All officers’ cabins have a bed, a desk and chair, a closet, sink and a small TV with news and sport provided by the British Forces Broadcasting Service, so the crew are kept up to date.

The only difference between them and the captain’s cabin is that the captain’s quarters are slightly larger, with extra chairs so the skipper can hold meetings with his most senior officers.

The source said: “The crew of the ship take very seriously the business of having a member of the Royal family on board, but they are being very relaxed and easy with him. He isn't someone that would want a fuss made of him.”

The Prince, who conducted two tours of Afghanistan during his decade as an Army officer, retired from his operational role in June 2015, though he officially remains an unpaid Army officer for life.

Wave Knight, launched in 2000 and accepted into service in 2003, provides fuel, food, fresh water, ammunition and other supplies to Royal Navy vessels operating in the area.

She is part of an international fleet of vessels engaged in anti-narcotics operations in the Caribbean and could be required to intercept suspect vessels while the Prince is on board.

In 2009, it was the Wave Knight whose crew witnessed the kidnapping by Somali pirates of the British couple Paul and Rachel Chandler, coming within 15m of the couple’s vessel but controversially deciding not to intervene for fear of endangering their lives.

Prince Harry is greeted by cultural dancers during his tour of the CaribbeanCredit:
Chris Jackson/Getty

The Prince is in the Caribbean at the personal request of the Queen, who is no longer able to accept invitations to visit countries so far away, and his performance is being “monitored closely” by Buckingham Palace, a source said, though it is not known whether he has spoken personally to the Queen.

Kensington Palace, meanwhile, has declined to comment on whether he has been keeping in touch with his girlfriend during the trip.